For certain light scanning microscopes, the confocal detection is generally optimal only for a predefined pupil diameter of the imaging lens system. Larger or smaller pupil diameters lead to poorer results, or even to loss of signal. Furthermore, if several spots are moved simultaneously in the predefined region of the sample, particularly in the case of thicker samples, there is the effect that a strong background signal occurs, since extrafocal light can pass through the pinholes and is detected. Moreover, disadvantageously, an undesired crosstalk can occur.